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From the Ronald O. Perelman Department of Dermatology, New York University

Abstract

A 13-year-old boy and a 7-year-old boy, who are brothers, presented with a life-long history of erythema, hyperkeratosis,
and desquamation of the hands and feet. Symptoms improved with the use of topical glucocorticoids and keratolytics. PPK of
Sybert is characterized by palmoplantar hyperkeratosis with transgrediens, autosomal dominant inheritance, and the absence
of associated systemic features.

Clinical summary

History.—A 13-year-old boy and his 7-year-old brother had a dermatosis of the hands and feet since birth. The two brothers, were evaluated
at New York University Medical Center's Dermatologic Associates in February 2000, with a life-long history of erythema and
scale of the hands and feet. The brothers had marked hyperhidrosis compared to an unaffected sibling. They had been treated
in the past with salicylic acid and topical glucocorticoids with some improvement. The patients had no systemic symptoms and
were otherwise healthy. There were no similar skin findings in other family members.

Physical examination.—Symmetric erythema, hyperkeratosis, and desquamation were present on the palms and soles in a stocking-glove distribution
with extension to the wrists, Achilles tendons, and the dorsal aspects of the hands and feet. Hyperkeratotic, erythematous
plaques were noted on the elbows and knees. Examination of the hair, nails, and teeth was normal.

Figure 1

Figure 2

Laboratory data.— None.

Histopathology.—There is epidermal hyperplasia with hypergranulosis, a thin layer of parakeratosis, and overlying orthokeratosis. There is
a slightly increased number of basal and suprabasal mitotic figures. There are dilated blood vessels in the papillary dermis
and a sparse infiltrate of lymphocytes. A periodic acid-Schiff stain is negative for fungi.

Diagnosis.—Palmoplantar keratoderma of Sybert.

Comment

The hereditary palmoplantar keratodermas (PPK) are a heterogeneous group of disorders characterized by hyperkeratosis of the
palms and soles. They are sometimes difficult to distinguish clinically, and diagnoses are made on the basis of morphologic
features, distribution of hyperkeratosis, the presence or absence of associated anomalies, and inheritance pattern [1]. Elucidation of underlying gene defects for many of the PPK's has aided in their classification [2].

PPK of Sybert, previously referred to as Greither's PPK, was described in 1952. It is an autosomal-dominant condition with
variable expression and is extremely rare, with only ten cases appearing in the literature [3]. PPK of Sybert is characterized by erythema, hyperkeratosis, and desquamation of the palms and soles with lateral and dorsal
extension, which characteristically involves the Achilles tendon [4]. In addition, hyperkeratotic plaques frequently occur on the elbows and knees [3, 4]. Hyperhidrosis is a typical feature, and pseudoainhum formation with autoamputation has been reported [5]. There are no associated extracutaneous anomalies.

The gene locus for PPK of Sybert is unknown. Ultrastructural studies do not demonstrate abnormal keratins other than those
associated with hyperproliferation. Although keratin filaments appear normal, keratohyalin granules are abnormal in distribution
and structure [5].

In milder cases, treatment with emollients, topical retinoids, keratolytics, and topical glucocorticoids has been used with
some success. Treatment with isotretinoin has been tried in one case with clinical improvement, which correlated directly
with dosage [5].